Meat trimming knives which are used in the meat processing industry for removing meat from bones, have a power driven circular-shaped cutting blade mounted on a manually movable handle. Examples of such circular cutting blades and meat trimming knives are shown in U.S. Pat. Nos. 3,024,532; 3,269,010; 4,324,043; and 4,363,170. The circular blades are removably mounted on the trimming knife and are generally sharpened by the meat trimmer or maintenance office personnel at the end of each work shift or every two or three days depending upon the particular trimming operation being performed to maintain a sharp cutting edge on the blade at all times. A sharp blade increases the efficiency of the trimming knife and reduces hand fatique of the operator.
These existing knife blades are sharpened by hand filing which, although producing a good result, is both time consuming and inaccurate unless performed by a skilled individual or by a sharpening device which was mounted directly on the cutting knife such as shown in U.S. Pat. No. 3,359,485, or by mounting the knife on a grinding machine such as shown in U.S. Pat. No. 3,406,486. These prior sharpeners either had to be located at the meat trimming station which is not satisfactory due to the cleanliness requirements and condition at the trimming stations, or required the knife to be disconnected from its power supply at the work station and carried to a remote sharpening station. Both of these prior sharpening devices are inconvenient and time consuming thereby increasing operating costs.
Another problem with existing knife sharpeners is that the operator when sharpening the knife, usually will remove more blade material than necessary in forming a sharp cutting edge since the sharpening is done by a trial and error technique usually until the operator believes or feels that the edge is sufficiently sharp. Removal of excess blade material even, when measured in thousands of an inch, reduces the blade life considerably by reducing the axial length of the blade requiring the operator to prematurely discard the blade.
Thus, the need has existed for a blade sharpener which will automatically ensure that only a predetermined quantity of material is removed from the blade edge sufficient to provide a sharpened cutting edge thereby increasing considerably the blade life, and in which only the blade, after removal from the meat trimming knife, is mounted on the sharpening device.